Liquid crystal display device

ABSTRACT

According to one embodiment, a liquid crystal display device includes a main pixel electrode having a first width in a first direction and a first edge extending in a second direction, and a sub-pixel electrode. The sub-pixel electrode has a second width, which is greater than the first width in the first direction, has a third width, which is a maximum width in the first direction at a central portion of the sub-pixel electrode, has a fourth width in the second direction at a position with a first distance from the first edge in the first direction, and has a fifth width, which is less than the fourth width at a position with a second distance, which is greater than the first distance, from the first edge in the first direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2011-165257, filed Jul. 28, 2011; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay device.

BACKGROUND

In recent years, flat-panel display devices have been vigorouslydeveloped. By virtue of such advantageous features as light weight,small thickness and low power consumption, special attention has beenpaid to liquid crystal display devices among others. In particular, inactive matrix liquid crystal devices in which switching elements areincorporated in respective pixels, attention is paid to theconfiguration which makes use of a lateral electric field (including afringe electric field), such as an IPS (In-Plane Switching) mode or anFFS (Fringe Field Switching) mode. Such a liquid crystal display deviceof the lateral electric field mode includes pixel electrodes and acounter-electrode, which are formed on an array substrate, and liquidcrystal molecules are switched by a lateral electric field which issubstantially parallel to a major surface of the array substrate.

On the other hand, there has been proposed a technique wherein a lateralelectric field or an oblique electric field is produced between a pixelelectrode formed on an array substrate and a counter-electrode formed ona counter-substrate, thereby switching liquid crystal molecules.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view which schematically illustrates a structure and anequivalent circuit of a liquid crystal display panel according to anembodiment.

FIG. 2 is a plan view which schematically shows a structure example of apixel at a time when a liquid crystal display panel shown in FIG. 1 isviewed from a counter-substrate side.

FIG. 3 is a plan view in an X-Y plane, in which a sub-pixel electrodeshown in FIG. 2 and a peripheral region thereof are enlarged.

FIG. 4 is a schematic cross-sectional view, taken along line A-A in FIG.2, showing a cross-sectional structure of the liquid crystal displaypanel shown in FIG. 2.

FIG. 5 is a view for explaining an electric field which is producedbetween a pixel electrode and a common electrode in the liquid crystaldisplay panel shown in FIG. 2, and a relationship between directors ofliquid crystal molecules by this electric field and a transmittance.

FIG. 6 is a view for explaining a relationship between an electricfield, which is produced between a pixel electrode and a commonelectrode in the liquid crystal display panel according to theembodiment, and a transmittance.

FIG. 7 is a view for explaining a relationship between an electricfield, which is produced between a pixel electrode and a commonelectrode in a liquid crystal display panel according to a comparativeexample, and a transmittance.

FIG. 8 is a plan view which schematically shows another structureexample of the pixel at a time when the liquid crystal display panelshown in FIG. 1 is viewed from the counter-substrate side.

FIG. 9 is a plan view which schematically shows another structureexample of the pixel at a time when the liquid crystal display panelshown in FIG. 1 is viewed from the counter-substrate side.

FIG. 10 is a plan view which schematically shows another structureexample of the pixel at a time when the liquid crystal display panelshown in FIG. 1 is viewed from the counter-substrate side.

FIG. 11 is a plan view which schematically shows another structureexample of the pixel at a time when the liquid crystal display panelshown in FIG. 1 is viewed from the counter-substrate side.

FIG. 12 is a plan view which schematically shows another structureexample of the pixel at a time when the liquid crystal display panelshown in FIG. 1 is viewed from the counter-substrate side.

FIG. 13 is a plan view which schematically shows a structure example ofthe pixel at a time when the liquid crystal display panel shown in FIG.1 is viewed from the counter-substrate side.

FIG. 14 is a plan view which schematically shows another structureexample at a time when an array substrate is viewed from thecounter-substrate side.

FIG. 15 is a plan view which schematically shows another structureexample at a time when the array substrate is viewed from thecounter-substrate side.

FIG. 16 is a plan view which schematically shows another structureexample at a time when the array substrate is viewed from thecounter-substrate side.

DETAILED DESCRIPTION

In general, according to one embodiment, a liquid crystal display deviceincludes a first substrate including a strip-shaped main pixel electrodehaving a first width in a first direction and linearly extending in asecond direction crossing the first direction, the main pixel electrodeincluding a first edge extending in the second direction, the firstsubstrate further including a sub-pixel electrode crossing the mainpixel electrode and protruding from the first edge in the firstdirection, and a first alignment film covering the main pixel electrodeand the sub-pixel electrode; a second substrate including main commonelectrodes extending substantially parallel to the main pixel electrodeon both sides of the main pixel electrode, and a second alignment filmcovering the main common electrodes; and a liquid crystal layerincluding liquid crystal molecules held between the first substrate andthe second substrate, wherein the sub-pixel electrode has a secondwidth, which is greater than the first width, in the first direction,has a third width, which is a maximum width in the first direction, at acentral portion of the sub-pixel electrode, has a fourth width in thesecond direction at a position with a first distance from the first edgein the first direction, and has a fifth width, which is less than thefourth width, at a position with a second distance, which is greaterthan the first distance, from the first edge in the first direction.

According to another embodiment, a liquid crystal display deviceincludes a first substrate including a first wiring line and a secondwiring line which neighbor with a distance in a first direction andextend in a second direction crossing the first direction, astrip-shaped main pixel electrode which is disposed between the firstwiring line and the second wiring line, has a first width in the firstdirection and linearly extends in the second direction, and a sub-pixelelectrode which crosses an intermediate portion in the second directionof the main pixel electrode and includes projection portions protrudingtoward the first wiring line and the second wiring line; a secondsubstrate including main common electrodes which are opposed to thefirst wiring line and the second wiring line and extend substantiallyparallel to the main pixel electrode; and a liquid crystal layerincluding liquid crystal molecules held between the first substrate andthe second substrate, wherein the sub-pixel electrode has a secondwidth, which is greater than the first width, in the first direction,has a third width, which is a maximum width in the first direction, at acentral portion of the sub-pixel electrode, has a fourth width in thesecond direction on the main pixel electrode side, and has a fifthwidth, which is less than the fourth width, in the second direction onthe first wiring line side and on the second wiring line side.

According to another embodiment, a liquid crystal display deviceincludes a first substrate including a first wiring line and a secondwiring line which neighbor with a distance in a first direction andextend in a second direction crossing the first direction, astrip-shaped main pixel electrode which is disposed between the firstwiring line and the second wiring line and includes a first edgelinearly extending in the second direction, and a sub-pixel electrodewhich includes a second edge extending in a direction different from thedirection of extension of the first edge, the second edge beingcontinuous with the first edge; a second substrate including main commonelectrodes which are opposed to the first wiring line and the secondwiring line and extend substantially parallel to the main pixelelectrode; and a liquid crystal layer including liquid crystal moleculesheld between the first substrate and the second substrate, wherein anexterior angle between the first edge and the second edge is an obtuseangle.

According to another embodiment, a liquid crystal display deviceincludes a first substrate including a first wiring line and a secondwiring line which neighbor with a distance in a first direction andextend in a second direction crossing the first direction, astrip-shaped main pixel electrode which is disposed between the firstwiring line and the second wiring line, has a first width in the firstdirection and linearly extends in the second direction, and a sub-pixelelectrode which crosses one end portion in the second direction of themain pixel electrode and includes projection portions protruding towardthe first wiring line and the second wiring line; a second substrateincluding main common electrodes which are opposed to the first wiringline and the second wiring line and extend substantially parallel to themain pixel electrode; and a liquid crystal layer including liquidcrystal molecules held between the first substrate and the secondsubstrate, wherein the sub-pixel electrode has a second width, which isgreater than the first width, in the first direction, has a third width,which is a maximum width in the first direction, at a central portion ofthe sub-pixel electrode, has a fourth width in the second direction onthe main pixel electrode side, and has a fifth width, which is less thanthe fourth width, in the second direction on the first wiring line sideand on the second wiring line side.

Embodiments will now be described in detail with reference to theaccompanying drawings. In the drawings, structural elements having thesame or similar functions are denoted by like reference numerals, and anoverlapping description is omitted.

FIG. 1 is a view which schematically shows a structure and an equivalentcircuit of a liquid crystal display device according to an embodiment.

Specifically, the liquid crystal display device includes anactive-matrix-type liquid crystal display panel LPN. The liquid crystaldisplay panel LPN includes an array substrate AR which is a firstsubstrate, a counter-substrate CT which is a second substrate that isdisposed to be opposed to the array substrate AR, and a liquid crystallayer LQ which is disposed between the array substrate AR and thecounter-substrate CT. The liquid crystal display panel LPN includes anactive area ACT which displays an image. The active area ACT is composedof a plurality of pixels PX which are arrayed in a matrix of m×n (m andn are positive integers).

The liquid crystal display panel LPN includes, in the active area ACT,an n-number of gate lines G (G1 to Gn), an n-number of storagecapacitance lines C (C1 to Cn), and an m-number of source lines S (S1 toSm). The gate lines G and storage capacitance lines C extend in a firstdirection X. The gate lines G and storage capacitance lines C neighborat intervals along a second direction Y crossing the first direction X,and are alternately arranged in parallel. In this example, the firstdirection X and the second direction Y are perpendicular to each other.The source lines S cross the gate lines G and storage capacitance linesC. The lines S extend substantially linearly along the second directionY. It is not always necessary that each of the gate lines G, storagecapacitance lines C and source lines S extend linearly, and a partthereof may be bent.

Each of the gate lines G is led out of the active area ACT and isconnected to a gate driver GD. Each of the source lines S is led out ofthe active area ACT and is connected to a source driver SD. At leastparts of the gate driver GD and source driver SD are formed on, forexample, the array substrate AR, and are connected to a driving IC chip2 which incorporates a controller.

Each of the pixels PX includes a switching element SW, a pixel electrodePE and a common electrode CE. A storage capacitance CS is formed, forexample, between the storage capacitance line C and the pixel electrodePE. The storage capacitance line C is electrically connected to avoltage application module VCS to which a storage capacitance voltage isapplied.

In the present embodiment, the liquid crystal display panel LPN isconfigured such that the pixel electrodes PE are formed on the arraysubstrate AR, and at least a part of the common electrode CE is formedon the counter-substrate CT, and liquid crystal molecules of the liquidcrystal layer LQ are switched by mainly using an electric field which isproduced between the pixel electrodes PE and the common electrode CE.The electric field, which is produced between the pixel electrodes PEand the common electrode CE, is an oblique electric field which isslightly inclined to an X-Y plane which is defined by the firstdirection X and second direction Y, or to a substrate major surface ofthe array substrate AR or a substrate major surface of thecounter-substrate CT (or a lateral electric field which is substantiallyparallel to the substrate major surface).

The switching element SW is composed of, for example, an n-channelthin-film transistor (TFT). The switching element SW is electricallyconnected to the gate line G and source line S. The switching element SWmay be of a top gate type or a bottom gate type. In addition, asemiconductor layer of the switching element SW is formed of, forexample, polysilicon, but it may be formed of amorphous silicon.

The pixel electrodes PE are disposed in the respective pixels PX, andare electrically connected to the switching elements SW. The commonelectrode CE has, for example, a common potential, and is disposedcommon to the pixel electrodes PE of plural pixels PX via the liquidcrystal layer LQ. The pixel electrodes PE and common electrode CE areformed of a light-transmissive, electrically conductive material such asindium tin oxide (ITO) or indium zinc oxide (IZO). However, the pixelelectrodes PE and common electrode CE may be formed of other metallicmaterial such as aluminum.

The array substrate AR includes a power supply module VS for applying avoltage to the common electrode CE. The power supply module VS isformed, for example, on the outside of the active area ACT. The commonelectrode CE is led out to the outside of the active area ACT, and iselectrically connected to the power supply module VS via an electricallyconductive member (not shown).

FIG. 2 is a plan view which schematically shows a structure example ofone pixel PX at a time when the liquid crystal display panel LPN shownin FIG. 1 is viewed from the counter-substrate side. FIG. 2 is a planview in an X-Y plane.

A gate line G1, a gate line G2 and a storage capacitance line C1 extendin the first direction X. A source line S1 and a source line S2 extendin the second direction Y. The storage capacitance line C1 is located ata substantially middle point between the gate line G1 and the gate lineG2. Specifically, the distance between the gate line G1 and the storagecapacitance line C1 in the second direction Y is substantially equal tothe distance between the gate line G2 and the storage capacitance lineC1 in the second direction Y.

In the example illustrated, the pixel PX corresponds to a grid regionwhich is formed by the gate line G1, gate line G2, source line S1 andsource line S2, as indicated by a broken line in FIG. 2. The pixel PXhas a rectangular shape having a greater length in the second directionY than in the first direction X. The length of the pixel PX in the firstdirection X corresponds to a pitch between the source line S1 and sourceline S2 in the first direction X. The length of the pixel PX in thesecond direction Y corresponds to a pitch between the gate line G1 andgate line G2 in the second direction Y. The pixel electrode PE isdisposed between the source line S1 and source line S2 which neighboreach other. In addition, the pixel electrode PE is located between thegate line G1 and gate line G2.

In the example illustrated, in the pixel PX, the source line S1 isdisposed at a left side end portion, the source line S2 is disposed at aright side end portion, the gate line G1 is disposed at an upper sideend portion, and the gate line G2 is disposed at a lower side endportion. Strictly speaking, the source line S1 is disposed to extendover a boundary between the pixel PX and a pixel neighboring on the leftside, the source line S2 is disposed to extend over a boundary betweenthe pixel PX and a pixel neighboring on the right side, the gate line G1is disposed to extend over a boundary between the pixel PX and a pixelneighboring on the upper side, and the gate line G2 is disposed toextend over a boundary between the pixel PX and a pixel neighboring onthe lower side. The storage capacitance line C1 is disposed at asubstantially central part of the pixel PX.

The switching element SW in the illustrated example is electricallyconnected to the gate line G1 and source line S1. The switching elementSW is provided at an intersection between the gate line G1 and sourceline S1. A drain line of the switching element SW is formed to extendalong the source line S1 and storage capacitance line C1, and iselectrically connected to the pixel electrode PE via a contact hole CHwhich is formed at an area overlapping the storage capacitance line C1.The switching element SW is provided in an area overlapping the sourceline S1 and storage capacitance line C1, and does not substantiallyprotrude from the area overlapping the source line S1 and storagecapacitance line C1, thus suppressing a decrease in area of an apertureportion which contributes to display.

The pixel electrode PE includes a main pixel electrode PA and asub-pixel electrode PB. The main pixel electrode PA and sub-pixelelectrode PB are formed to be integral or continuous, and areelectrically connected to each other. In the meantime, in the exampleillustrated, only the pixel electrode PE which is disposed in one pixelPX is shown, but pixel electrodes of the same shape are disposed inother pixels, the depiction of which is omitted.

The main pixel electrode PA is located between the source line S1 andsource line S2. In the illustrated example, the sub-pixel electrode PBcrosses an intermediate portion in the second direction Y of the mainpixel electrode PA. Accordingly, the main pixel electrode PA linearlyextends in the second direction Y from the intersection with thesub-pixel electrode PB to the vicinity of the upper side end portion ofthe pixel PX and to the vicinity of the lower side end portion of thepixel PX. Specifically, the pixel electrode PE is formed in a crossshape. In addition, the main pixel electrode PA is disposed at asubstantially middle position between the source line S1 and source lineS2, that is, at a center of the pixel PX. The distance in the firstdirection X between the source line S1 and the main pixel electrode PAis substantially equal to the distance in the first direction X betweenthe source line S2 and the main pixel electrode PA. The main pixelelectrode PA is formed in a strip shape having a substantially equalwidth W1 in the first direction X. In addition, the main pixel electrodePA has first edges E1 which linearly extend in the second direction Y.The first edges E1 are located, with an interval of the width W1, on thesource line S1 side of the main pixel electrode PA and on the sourceline S2 side of the main pixel electrode PA, respectively.

The sub-pixel electrode PB crosses the main pixel electrode PA andextends along the first direction X. Alternatively, the sub-pixelelectrode PB protrudes from the first edges E1 of the main pixelelectrode PA in the first direction X. The sub-pixel electrode PBincludes projection portions which protrude from the intersection withthe main pixel electrode PA toward the source line S1 and source lineS2. Specifically, that region of the sub-pixel electrode PB, whichprotrudes from the main pixel electrode PA toward the source line S1,corresponds to a projection portion PB1, and that region of thesub-pixel electrode PB, which protrudes from the main pixel electrode PAtoward the source line S2, corresponds to a projection portion PB2. Theprojection portion PB1 and projection portion PB2 are located on bothsides of the main pixel electrode PA, have the same shape, and areline-symmetric with respect to a center line O of the main pixelelectrode PA, which extends in the second direction Y. The sub-pixelelectrode PB includes second edges E2 which are continuous with thefirst edges E1. The second edges E2 extend in directions different fromthe direction of the first edges E1, that is, in directions differentfrom the second direction Y. The shape of the sub-pixel electrode PBwill be described later in detail.

In the example illustrated, the sub-pixel electrode PB is opposed to thestorage capacitance line C1. Specifically, the projection portion PB1and projection portion PB2 of the sub-pixel electrode PB, as a whole,are located in an area overlapping the storage capacitance line C1. Thesub-pixel electrode PB is electrically connected to the switchingelement SW via the contact hole CH.

The common electrode CE includes main common electrodes CA. The maincommon electrodes CA extend, in the X-Y plane, linearly in the seconddirection Y that is substantially parallel to the main pixel electrodePA, on both sides of the main pixel electrode PA. Alternatively, themain common electrodes CA are opposed to the source lines S which extendin the second direction Y, and extend substantially in parallel to themain pixel electrode PA. The main common electrode CA is formed in astrip shape having a substantially equal width W1 in the first directionX.

In the example illustrated, two main common electrodes CA are arrangedin parallel with a distance in the first direction. Specifically, themain common electrodes CA include a main common electrode CAL disposedat the left side end portion of the pixel PX, and a main commonelectrode CAR disposed at the right side end portion of the pixel PX.Strictly speaking, the main common electrode CAL is disposed to extendover a boundary between the pixel PX and a pixel neighboring on the leftside, and the main common electrode CAR is disposed to extend over aboundary between the pixel PX and a pixel neighboring on the right side.The main common electrode CAL is opposed to the source line S1, and themain common electrode CAR is opposed to the source line S2. The maincommon electrode CAL and the main common electrode CAR are electricallyconnected to each other within the active area or outside the activearea.

Paying attention to the positional relationship between the pixelelectrode PE and the main common electrodes CA, the pixel electrode PEand the main common electrodes CA are alternately arranged along thefirst direction X. The main pixel electrode PA and the main commonelectrodes CA are disposed in parallel to each other. In this case, inthe X-Y plane, each of the main common electrodes CA does not overlapthe pixel electrode PE.

One pixel electrode PE is located between the main common electrode CALand main common electrode CAR which neighbor each other. In other words,the main common electrode CAL and main common electrode CAR are disposedon both sides of a position immediately above the pixel electrode PE.Alternatively, the pixel electrode PE is disposed between the maincommon electrode CAL and main common electrode CAR. Thus, the maincommon electrode CAL, main pixel electrode PA and main common electrodeCAR are arranged in the named order along the first direction X.

The main pixel electrode PA is located at a substantially middle pointbetween the main common electrode CAL and main common electrode CAR.Specifically, the distance between the main common electrode CAL and themain pixel electrode PA in the first direction X is substantially equalto the distance between the main common electrode CAR and the main pixelelectrode PA in the first direction X.

FIG. 3 is a plan view in the X-Y plane, in which the sub-pixel electrodePB shown in FIG. 2 and a peripheral region thereof are enlarged. FIG. 3shows only parts which are necessary for the description.

In the example illustrated, the projection portion PB1 of the sub-pixelelectrode PB, which is disposed between the main pixel electrode PA andthe source line S1, and the projection portion PB2 of the sub-pixelelectrode PB, which is disposed between the main pixel electrode PA andthe source line S2, have triangular shapes, respectively, and, to bemore specific, have isosceles-triangular shapes. Specifically, each ofthe projection portion PB1 and projection portion PB2 includes anoblique line E21 and an oblique line E22 which are inclined to the firstdirection X, and a base E23 which is located on the same straight lineas the first edge E1. When the length of the base E23 is equal to eachof the oblique line E21 and oblique line E22, each of the projectionportion PB1 and projection portion PB2 has an equilateral-triangularshape. The oblique line E21 and oblique line E22 correspond to a pair ofsecond edges E2 each having a linear shape. The length of the obliqueline E21 is equal to the length of the oblique line E22. The obliqueline E21 is not parallel to the oblique line E22. An intersectionbetween the oblique line E21 and oblique line E22 in the projectionportion PB1, that is, an apex T1 of the projection portion PB1, islocated at a position closest to the source line S1 or main commonelectrode CAL. An intersection between the oblique line E21 and obliqueline E22 in the projection portion PB2, that is, an apex T2 of theprojection portion PB2, is located at a position closest to the sourceline S2 or main common electrode CAR.

Since the sub-pixel electrode PB crosses the intermediate portion of themain pixel electrode PA, an exterior angle θ1 is formed at fourlocations between the main pixel electrode PA and the sub-pixelelectrodes PB. The exterior angle θ1 corresponds to an angle formedbetween the first edge E1 and the linear second edge E2. Each of theexterior angles θ1 at the four locations is an obtuse angle which isgreater than 90°. The exterior angles θ1 at the four locations in theFigure are substantially equal. Thus, the sum of the exterior angles θ1at the four locations is greater than 360°. For example, the exteriorangle θ1 is 135°. In other words, an interior angle θ2 between the baseE23 and the second edge E2 is an acute angle.

Paying attention to the width of the sub-pixel electrode PB in the firstdirection X, a width W2 in the first direction X between the obliqueline E21 of the projection portion PB1 and the oblique line E21 of theprojection portion PB2 is greater than the width W1 of the main pixelelectrode PA. A width W3 in the first direction X between the apex T1 ofthe projection portion PB1 and the apex T2 of the projection portion PB2is greater than the width W2 and is the maximum width. A width W4 in thefirst direction X between the oblique line E22 of the projection portionPB1 and the oblique line E22 of the projection portion PB2 is greaterthan the width W1 and is less than the width W3. Specifically, thesub-pixel electrode PB has the width W3, which is the maximum width inthe first direction X, at the central portion of the sub-pixel electrodePB in the second direction Y, and has a width, which is greater than thewidth W1 and is less than the width W3, on both sides of this centralportion.

Paying attention to the width in the second direction Y of the sub-pixelelectrode PB, this width gradually decreases in a direction away fromthe main pixel electrode PA (or in a direction toward the source line orthe main common electrode). Specifically, the projection portion PB1 ofthe sub-pixel electrode PB has a width W11 at a position (a position onthe main pixel electrode PA side) with a distance D1 in the firstdirection X from the first edge E1 (or the base E23), and a width W12,which is less than the width W11, at a position (a position on thesource line S1 side or a position on the main common electrode CAL side)with a distance D2, which is greater than the distance D1, in the firstdirection X from the first edge E1. Similarly, the projection portionPB2 of the sub-pixel electrode PB has the width W11 at a position on themain pixel electrode PA side, and has the width W12, which is less thanthe width W11, at a position on the source line S2 side or a position onthe main common electrode CAR side).

FIG. 4 is a schematic cross-sectional view, taken along line A-A in FIG.2, showing a cross-sectional structure of the liquid crystal displaypanel LPN shown in FIG. 2. FIG. 4 shows only parts which are necessaryfor the description.

A backlight 4 is disposed on the back side of the array substrate ARwhich constitutes the liquid crystal display panel LPN. Various modesare applicable to the backlight 4. As the backlight 4, use may be madeof either a backlight which utilizes a light-emitting diode (LED) as alight source, or a backlight which utilizes a cold cathode fluorescentlamp (CCFL) as a light source. A description of the detailed structureof the backlight 4 is omitted.

The array substrate AR is formed by using a first insulative substrate10 having light transmissivity. Source lines S are formed on a firstinterlayer insulation film 11, and are covered with a second interlayerinsulation film 12. Gate lines and storage capacitance lines, which arenot shown, are disposed, for example, between the first insulativesubstrate 10 and the first interlayer insulation film 11. Pixelelectrodes PE are formed on the second interlayer insulation film 12.Each pixel electrode PE is located on the inside of a positionimmediately above each of neighboring source lines S. A first alignmentfilm AL1 is disposed on that surface of the array substrate AR, which isopposed to the counter-substrate CT, and the first alignment film AL1extends over substantially the entirety of the active area ACT. Thefirst alignment film AL1 covers the pixel electrode PE, etc., and isalso disposed over the second interlayer insulation film 12. The firstalignment film AL1 is formed of a material which exhibits horizontalalignment properties. In the meantime, the array substrate AR mayinclude a part of the common electrode CE.

The counter-substrate CT is formed by using a second insulativesubstrate 20 having light transmissivity. The counter-substrate CTincludes a black matrix BM, a color filter CF, an overcoat layer OC, acommon electrode CE, and a second alignment film AL2.

The black matrix BM partitions the pixels PX and forms aperture portionsAP which are opposed to the pixel electrodes PE. Specifically, the blackmatrix BM is disposed so as to be opposed to wiring portions, such asthe source lines S, gate lines, storage capacitance lines, and switchingelements. In this example, only those portions of the black matrix BM,which extend in the second direction Y, are depicted, but the blackmatrix BM may include portions extending in the first direction X. Theblack matrix BM is disposed on an inner surface 20A of the secondinsulative substrate 20, which is opposed to the array substrate AR.

The color filter CF is disposed in association with each pixel PX.Specifically, the color filter CF is disposed in the aperture portion APon the inner surface 20A of the second insulative substrate 20, and apart of the color filter CF extends over the black matrix BM. Colorfilters CF, which are disposed in the pixels PX neighboring in the firstdirection X, have mutually different colors. For example, the colorfilters CF are formed of resin materials which are colored in threeprimary colors of red, blue and green. A red color filter CFR, which isformed of a resin material that is colored in red, is disposed inassociation with a red pixel. A blue color filter CFB, which is formedof a resin material that is colored in blue, is disposed in associationwith a blue pixel. A green color filter CFG, which is formed of a resinmaterial that is colored in green, is disposed in association with agreen pixel. Boundaries between these color filters CF are located atpositions overlapping the black matrix BM. The overcoat layer OC coversthe color filters CF. The overcoat layer OC reduces the effect ofasperities on the surface of the color filters CF. The overcoat layer OCis formed of, for example, a transparent resin material.

The common electrode CE is formed on that side of the overcoat layer OC,which is opposed to the array substrate AR. The main common electrodesCA are located above the source line S. The second alignment film AL2 isdisposed on that surface of the counter-substrate CT, which is opposedto the array substrate AR, and the second alignment film AL2 extendsover substantially the entirety of the active area ACT. The secondalignment film AL2 covers the common electrodes CE and overcoat layerOC. The second alignment film AL2 is formed of a material which exhibitshorizontal alignment properties.

The first alignment film AL1 and second alignment film AL2 are subjectedto alignment treatment (e.g. rubbing treatment or optical alignmenttreatment) for initially aligning the liquid crystal molecules of theliquid crystal layer LQ. A first alignment treatment direction PD1, inwhich the first alignment film AL1 initially aligns the liquid crystalmolecules, is parallel to a second alignment treatment direction PD2, inwhich the second alignment film AL2 initially aligns the liquid crystalmolecules. In an example shown in part (A) of FIG. 2, the firstalignment treatment direction PD1 and second alignment treatmentdirection PD2 are parallel to each other and are identical. In anexample shown in part (B) of FIG. 2, the first alignment treatmentdirection PD1 and second alignment treatment direction PD2 are parallelto each other and are opposite to each other.

The above-described array substrate AR and counter-substrate CT aredisposed such that their first alignment film AL1 and second alignmentfilm AL2 are opposed to each other. In this case, columnar spacers,which are formed of, e.g. a resin material so as to be integral to oneof the array substrate AR and counter-substrate CT, are disposed betweenthe first alignment film AL1 of the array substrate AR and the secondalignment film AL2 of the counter-substrate CT. Thereby, a predeterminedcell gap, for example, a cell gap of 2 to 7 μm, is created. The arraysubstrate AR and counter-substrate CT are attached by a sealant SB onthe outside of the active area ACT in the state in which thepredetermined cell gap is created therebetween.

The liquid crystal layer LQ is held in the cell gap which is createdbetween the array substrate AR and the counter-substrate CT, and isdisposed between the first alignment film AL1 and second alignment filmAL2. The liquid crystal layer LQ includes liquid crystal molecules LM.The liquid crystal layer LQ is composed of a liquid crystal materialhaving a positive (positive-type) dielectric constant anisotropy.

A first optical element OD1 is attached, by, e.g. an adhesive, to anouter surface 10B of the first insulative substrate 10 which constitutesthe array substrate AR. The first optical element OD1 is located on thatside of the liquid crystal display panel LPN, which is opposed to thebacklight 4, and controls the polarization state of incident light whichenters the liquid crystal display panel LPN from the backlight 4. Thefirst optical element OD1 includes a first polarizer PL1 having a firstpolarization axis (or first absorption axis) AX1. In the meantime,another optical element, such as a retardation plate, may be disposedbetween the first polarizer PL1 and the first insulative substrate 10.

A second optical element OD2 is attached, by, e.g. an adhesive, to anouter surface 20B of the second insulative substrate 20 whichconstitutes the counter-substrate CT. The second optical element OD2 islocated on the display surface side of the liquid crystal display panelLPN, and controls the polarization state of emission light emerging fromthe liquid crystal display panel LPN. The second optical element OD2includes a second polarizer PL2 having a second polarization axis (orsecond absorption axis) AX2. In the meantime, another optical element,such as a retardation plate, may be disposed between the secondpolarizer PL2 and the second insulative substrate 20.

The first polarization axis AX1 of the first polarizer PL1 and thesecond polarization axis AX2 of the second polarizer PL2 have apositional relationship of crossed Nicols. In this case, one of thepolarizers is disposed such that the polarization axis thereof isparallel or perpendicular to an initial alignment direction of liquidcrystal molecules LM, that is, the first alignment treatment directionPD1 or second alignment treatment direction PD2. When the initialalignment direction is parallel to the second direction Y, thepolarization axis of one polarizer is parallel to the second direction Yor is parallel to the first direction X.

In an example shown in part (a) of FIG. 2, the first polarizer PL1 isdisposed such that the first polarization axis AX1 thereof isperpendicular to the second direction Y that is the initial alignmentdirection of liquid crystal molecules LM, and the second polarizer PL2is disposed such that the second polarization axis AX2 thereof isparallel to the initial alignment direction of liquid crystal moleculesLM. In addition, in an example shown in part (b) of FIG. 2, the secondpolarizer PL2 is disposed such that the second polarization axis AX2thereof is perpendicular to the second direction Y that is the initialalignment direction of liquid crystal molecules LM, and the firstpolarizer PL1 is disposed such that the first polarization axis AX1thereof is parallel to the initial alignment direction of liquid crystalmolecules LM.

Next, the operation of the liquid crystal display panel LPN having theabove-described structure is described with reference to FIG. 2 to FIG.4.

Specifically, in a state in which no voltage is applied to the liquidcrystal layer LQ, that is, in a state (OFF time) in which no electricfield is produced between the pixel electrode PE and common electrodeCE, the liquid crystal molecule LM of the liquid crystal layer LQ isaligned such that the major axis thereof is positioned in the firstalignment treatment direction PD1 of the first alignment film AL1 andthe second alignment treatment direction PD2 of the second alignmentfilm AL2. This OFF time corresponds to the initial alignment state, andthe alignment direction of the liquid crystal molecule LM at the OFFtime corresponds to the initial alignment direction.

Strictly speaking, the liquid crystal molecule LM is not always alignedin parallel to the X-Y plane, and, in many cases, the liquid crystalmolecule LM is pre-tilted. Thus, the initial alignment direction of theliquid crystal molecule LM corresponds to a direction in which the majoraxis of the liquid crystal molecule LM at the OFF time is orthogonallyprojected onto the X-Y plane. In the description below, for the purposeof simplicity, it is assumed that the liquid crystal molecule LM isaligned in parallel to the X-Y plane, and the liquid crystal molecule LMrotates in a plane parallel to the X-Y plane.

In this case, each of the first alignment treatment direction PD1 andthe second alignment treatment direction PD2 is substantially parallelto the second direction Y. At the OFF time, the liquid crystal moleculeLM is initially aligned such that the major axis thereof issubstantially parallel to the second direction Y. Specifically, theinitial alignment direction of the liquid crystal molecule LM isparallel to the second direction Y (or 0° to the second direction Y).

When the first alignment treatment direction PD1 and the secondalignment treatment direction PD2 are parallel and identical to eachother, as in the example illustrated, the liquid crystal molecules LMare substantially horizontally aligned (the pre-tilt angle issubstantially zero) in the middle part of the liquid crystal layer LQ inthe cross section of the liquid crystal layer LQ, and the liquid crystalmolecules LM become symmetric in the vicinity of the first alignmentfilm AL1 and in the vicinity of the second alignment film AL2, withrespect to the middle part as the boundary (splay alignment). In thestate in which the liquid crystal molecules LM are splay-aligned,optical compensation can be made by the liquid crystal molecules LM inthe vicinity of the first alignment film AL1 and the liquid crystalmolecules LM in the vicinity of the second alignment film AL2, even in adirection inclined to the normal direction of the substrate. Therefore,when the first alignment treatment direction PD1 and the secondalignment treatment direction PD2 are parallel and identical to eachother, light leakage is small in the case of black display, a highcontrast ratio can be realized, and the display quality can be improved.

In the meantime, when the first alignment treatment direction PD1 andthe second alignment treatment direction PD2 are parallel and oppositeto each other, the liquid crystal molecules LM are aligned withsubstantially equal pre-tilt angles, in the cross section of the liquidcrystal layer LQ, in the vicinity of the first alignment film AL1, inthe vicinity of the second alignment film AL2, and in the middle part ofthe liquid crystal layer LQ (homogeneous alignment).

Part of light from the backlight 4 passes through the first polarizerPL1 and enters the liquid crystal display panel LPN. The polarizationstate of the light, which enters the liquid crystal display panel LPN,is linear polarization perpendicular to the first polarization axis AX1of the first polarizer PL1. The polarization state of such linearpolarization hardly varies when the light passes through the liquidcrystal display panel LPN at the OFF time. Thus, the linearly polarizedlight, which has passed through the liquid crystal display panel LPN, isabsorbed by the second polarizer PL2 that is in the positionalrelationship of crossed Nicols in relation to the first polarizer PL1(black display).

On the other hand, in a state in which a voltage is applied to theliquid crystal layer LQ, that is, in a state (ON time) in which apotential difference is produced between the pixel electrode PE andcommon electrode CE, a lateral electric field (or an oblique electricfield), which is substantially parallel to the substrates, is producedbetween the pixel electrode PE and the common electrode CE. The liquidcrystal molecules LM are affected by the electric field, and the majoraxes thereof rotate within a plane which is parallel to the X-Y plane,as indicated by solid lines in the Figure.

In the example shown in FIG. 2, the liquid crystal molecule LM in alower half part of the region between the pixel electrode PE and maincommon electrode CAL rotates clockwise relative to the second directionY, and is aligned in a lower left direction in the Figure. The liquidcrystal molecule LM in an upper half part of the region between thepixel electrode PE and main common electrode CAL rotatescounterclockwise relative to the second direction Y, and is aligned inan upper left direction in the Figure. The liquid crystal molecule LM ina lower half part of the region between the pixel electrode PE and maincommon electrode CAR rotates counterclockwise relative to the seconddirection Y, and is aligned in a lower right direction in the Figure.The liquid crystal molecule LM in an upper half part of the regionbetween the pixel electrode PE and main common electrode CAR rotatesclockwise relative to the second direction Y, and is aligned in an upperlower right direction in the Figure.

As has been described above, in the state in which the electric field isproduced between the pixel electrode PE and common electrode CE in eachpixel PX, the liquid crystal molecules LM are aligned in a plurality ofdirections, with boundaries at positions overlapping the pixel electrodePE, and domains are formed in the respective alignment directions.Specifically, a plurality of domains are formed in one pixel PX.

At such ON time, linearly polarized light perpendicular to the firstpolarization axis AX1 of the first polarizer PL1 enters the liquidcrystal display panel LPN, and the polarization state of the lightvaries depending on the alignment state of the liquid crystal moleculesLM when the light passes through the liquid crystal layer LQ. At the ONtime, at least part of the light emerging from the liquid crystal layerLQ passes through the second polarizer PL2 (white display).

FIG. 5 is a view for explaining an electric field which is producedbetween the pixel electrode PE and common electrode CE in the liquidcrystal display panel LPN shown in FIG. 2, and a relationship betweendirectors of liquid crystal molecules LM by this electric field and atransmittance.

In the OFF state, the liquid crystal molecules are initially aligned ina direction which is substantially parallel to the second direction Y.In the ON state in which a potential difference is produced between thepixel electrode PE and the common electrode CE, when the director of theliquid crystal molecule LM (or the major-axis direction of the liquidcrystal molecule LM) deviates by about 45° from the first polarizationaxis AX1 of the first polarizer PL1 and from the second polarizationaxis AX2 of the second polarizer PL2, the optical modulation ratio ofthe liquid crystal layer LQ is highest (i.e. the transmittance at theaperture portion is highest).

In the example illustrated, in the ON state, the director of the liquidcrystal molecule LM between the main common electrode CAL and the pixelelectrode PE is substantially parallel to a 45°-225° azimuth directionin the X-Y plane, and the director of the liquid crystal molecule LMbetween the main common electrode CAR and the pixel electrode PE issubstantially parallel to a 135°-315° azimuth direction in the X-Yplane, and a peak transmittance is obtained. Meanwhile, when thedirector of the liquid crystal molecule LM is substantially parallel toa 0°-180° azimuth direction in the X-Y plane or substantially parallelto a 90°-270° azimuth direction in the X-Y plane, the transmittance atthe aperture portion becomes lowest.

In the ON state, if attention is paid to the transmittance distributionper pixel, the liquid crystal molecules LM over the pixel electrode PEand common electrode CE hardly rotate from the initial alignmentdirection. In other words, the directors of the liquid crystal moleculesLM are substantially parallel to the 90°-270° azimuth direction. Thus,the transmittance is substantially zero. On the other hand, a hightransmittance can be obtained over almost the entire area of theinter-electrode gaps between the pixel electrode PE and the commonelectrode CE.

Each of the main common electrode CAL that is located immediately abovethe source line S1 and the main common electrode CAR that is locatedimmediately above the source line S2 is opposed to the black matrix BM.Each of the main common electrode CAL and main common electrode CAR hasa width which is equal to or less than the width of the black matrix BMin the first direction X, and does not extend toward the pixel electrodePE from the position overlapping the black matrix BM. Thus, the apertureportion in each pixel, which contributes to display, corresponds toregions between the pixel electrode PE and main common electrode CAL andbetween the pixel electrode PE and main common electrode CAR, theseregions being included in the region between the black matrixes BM orthe region between the source line S1 and source line S2.

In the present embodiment, the pixel electrode PE includes the sub-pixelelectrode PB which has the width W11 at the position near the main pixelelectrode PA, and has the width W12, which is less than the width W11,at the position away from the main pixel electrode PA. Therefore, a hightransmittance can be obtained in the aperture portion. This point willbe concretely described below.

FIG. 6 is a view for explaining a relationship between the electricfield, which is produced between the pixel electrode PE and commonelectrode CE in the liquid crystal display panel LPN according to theembodiment, and a transmittance. A description is given of, by way ofexample, the relationship between the electric field produced betweenthe projection portion PB1 of the sub-pixel electrode PB, whichprotrudes from the main pixel electrode PA, and the main commonelectrode CAL, and the transmittance. The example illustratedcorresponds to an example in which the width of the sub-pixel electrodePB in the second direction Y gradually decreases in a direction awayfrom the main pixel electrode PA, or an example in which the exteriorangle θ1 between the first edge E1 of main pixel electrode PA and thesecond edge E2, which is continuous with the first edge E1, is an obtuseangle.

At the ON time, an electric field is produced between the main pixelelectrode PA and sub-pixel electrode PB, on one hand, and the maincommon electrode CAL, on the other hand. In the region where thealignment state of liquid crystal molecules LM has changed from theinitial alignment state, backlight passes and this region becomes alight part (white display). However, even at the ON time, as describedabove, in the region overlapping the pixel electrode PE and commonelectrode CE, the alignment state of liquid crystal molecules LM hardlychanges from the initial alignment state, no backlight passes and thisregion becomes a dark part (black display). In the meantime, in theregions overlapping the storage capacitance line C1 extending in thefirst direction X immediately below the sub-pixel electrode PB, the gateline (not shown) and the source line, since these lines are formed ofopaque wiring materials, no backlight passes regardless or the ON timeor OFF time, and these regions become dark parts.

At the ON time, the direction of an electric field, which extends fromthe intersection E12 between the first edge E1 and second edge E2 towardthe main common electrode CAL, becomes close to the 45°-225° azimuthdirection or the 135°-315° azimuth direction in the X-Y plane. Thus, inthe region which does not overlap the storage capacitance line C1 and isclose to the intersection E12, the liquid crystal molecule LM is alignedin a direction which becomes close to the 45°-225° azimuth direction orthe 135°-315° azimuth direction in which the transmittance is highest.Specifically, in the region near the intersection E12, backlight passesand this region becomes a light part (white display).

On the other hand, the direction of an electric field, which extendsfrom the vicinity of the apex T1 of the projection portion PB1 towardthe main common electrode CAL, becomes close to the 0°-180° azimuthdirection in the X-Y plane. Thus, the liquid crystal molecule LM in theregion is aligned in a direction which becomes close to the 0°-180°azimuth direction. This region becomes a dark part through which nobacklight passes. However, since this region is located immediatelyabove the storage capacitance line C1 and becomes a dark part regardlessof the alignment state of liquid crystal molecules LM, and there is nosubstantial loss in transmittance.

According to the structure of the present embodiment, the occurrence ofa dark part in the vicinity of the intersection E12, at which the firstedge E1 and second edge E2 are made continuous, can be suppressed, andthe transmittance can be improved.

FIG. 7 is a view for explaining a relationship between an electricfield, which is produced between a pixel electrode PE and a commonelectrode CE in a liquid crystal display panel LPN according acomparative example, and a transmittance. The example illustratedcorresponds to an example in which the width of a sub-pixel electrode PBin the second direction Y is constant regardless of the distance fromthe main pixel electrode PA, or an example in which the exterior angleθ1 between the first edge E1 of main pixel electrode PA and the secondedge E2 of sub-pixel electrode PB, which is continuous with the firstedge E1, is a right angle.

At the ON time, an electric field is produced between the main pixelelectrode PA and sub-pixel electrode PB, on one hand, and the maincommon electrode CAL, on the other hand. At such ON time, the directionof an electric field, which extends from the intersection E12 betweenthe first edge E1 and second edge E2 toward the main common electrodeCAL, becomes close to the 90°-270° azimuth direction. In particular, ata position near the intersection E12, the electric field is producedalong the first edge E1. Thus, in the region which does not overlap thestorage capacitance line C1 and is close to the intersection E12, theliquid crystal molecule LM is aligned in a direction which becomes closeto the 90°-270° azimuth direction in which the transmittance is lowest.Specifically, in this region, no backlight passes and this regionbecomes a dark part (black display).

As has been described above, according to the structure of thecomparative example, since the dark part occurs near the intersectionE12 between the first edge E1 and second edge E2, loss occurs intransmittance. In other words, in the comparative example shown in FIG.7, compared to the embodiment shown in FIG. 6, the transmittance lowers.In the comparative example shown in FIG. 7, the case has been describedthat the exterior angle θ1 between the first edge E1 and the second edgeE2 is the right angle. As the exterior angle θ1 becomes further smallerthan 90°, the direction of the electric field produced between theintersection E12 and the main common electrode CAL becomes closer to the90°-270° azimuth direction, the dark part becomes larger, and the lossin transmittance increases.

In order to confirm the above-described phenomenon, the inventorprepared a liquid crystal display device corresponding to the presentembodiment shown in FIG. 6 and a liquid crystal display devicecorresponding to the comparative example shown in FIG. 7, and measuredthe transmittance in the ON state in which the same voltage was appliedto the liquid crystal layers LQ. In the liquid crystal display devicecorresponding to the present embodiment, the exterior angle θ1 betweenthe first edge E1 of the main pixel electrode PA and the second edge E2of the sub-pixel electrode PB, which is continuous with the first edgeE1, was set at 135°. In the liquid crystal display device correspondingto the comparative example, the exterior angle θ1 between the first edgeE1 and the second edge E2 was set at 80°. The other conditions are thesame. Specifically, the width of the main pixel electrode PA in thefirst direction X was set at 5 μm, the width of the main commonelectrode CA in the first direction X was set at 5 μm, a horizontalinter-electrode distance between the main pixel electrode PA and themain common electrode CA in the first direction X was set at 10 μm, thepixel pitch was set at 30 μm, and the cell gap was set at 4 μm.

When the transmittance in the liquid crystal display devicecorresponding to the comparative example was set at 1, the transmittanceof 1.05 was successfully obtained in the liquid crystal display devicecorresponding to the present embodiment.

According to the present embodiment, the occurrence of a dark part inthe vicinity of the intersection between the main pixel electrode PA ofthe pixel electrode PE, which is included in the array substrate AR, andthe sub-pixel electrode PB, which is continuous with the main pixelelectrode PA, can be suppressed, and the decrease in transmittance canbe suppressed. Thereby, a good display quality can be obtained.

In addition, according to the present embodiment, a high transmittancecan be obtained in the inter-electrode gap between the pixel electrodePE and the common electrode CE. Thus, a transmittance per pixel cansufficiently be increased by increasing the inter-electrode distancebetween the main pixel electrode and the main common electrode. Asregards product specifications in which the pixel pitch is different,the peak condition of the transmittance distribution, as shown in FIG.5, can be used by varying the inter-electrode distance. Specifically, inthe display mode of the present embodiment, products with various pixelpitches can be provided by setting the inter-electrode distance, withoutnecessarily requiring fine electrode processing, as regards the productspecifications from low-resolution product specifications with arelatively large pixel pitch to high-resolution product specificationswith a relatively small pixel pitch. Therefore, requirements for hightransmittance and high resolution can easily be realized.

According to the present embodiment, as shown in FIG. 5, if attention ispaid to the transmission distribution in the region overlapping theblack matrix BM, the transmittance is sufficiently lowered. The reasonfor this is that the electric field does not leak to the outside of thepixel from the position of the common electrode CE, and an undesiredlateral electric field does not occur between pixels which neighbor eachother with the black matrix BM interposed, and therefore the liquidcrystal molecules in the region overlapping the black matrix BM keep theinitial alignment state, like the case of the OFF time (or black displaytime). Accordingly, even when the colors of the color filters aredifferent between neighboring pixels, the occurrence of color mixturecan be suppressed, and the decrease in color reproducibility or thedecrease in contrast ratio can be suppressed.

When misalignment occurs between the array substrate AR and thecounter-substrate CT, there are cases in which a difference occurs inthe horizontal inter-electrode distance between the pixel electrode PEand the common electrodes CE on both sides of the pixel electrode PE.However, since such misalignment commonly occurs in all pixels PX, theelectric field distribution does not differ between the pixels PX, andthe influence on the display of images is very small. In addition, evenwhen misalignment occurs between the array substrate AR and thecounter-substrate CT, leakage of an undesired electric field to theneighboring pixel can be suppressed. Thus, even when the colors of thecolor filters differ between neighboring pixels, the occurrence of colormixture can be suppressed, and the decrease in color reproducibility orthe decrease in contrast ratio can be suppressed.

According to the present embodiment, the main common electrodes CA areopposed to the source lines S. In particular, when the main commonelectrode CAL and main common electrode CAR are disposed immediatelyabove the source line S1 and source line S2, respectively, the apertureportion AP can be increased and the transmittance of the pixel PX can beimproved, compared to the case in which the main common electrode CALand main common electrode CAR are disposed on the pixel electrode PEside of the source line S1 and source line S2.

Furthermore, by disposing the main common electrode CAL and main commonelectrode CAR immediately above the source line S1 and source line S2,respectively, the inter-electrode distance between the pixel electrodePE, on one hand, and the main common electrode CAL and main commonelectrode CAR, on the other hand, can be increased, and a lateralelectric field, which is closer to a horizontal lateral electric field,can be produced. Therefore, a wide viewing angle, which is the advantageof an IPS mode, etc. in the conventional structure, can be maintained.

According to the present embodiment, a plurality of domains can beformed in one pixel. Thus, the viewing angle can optically becompensated in plural directions, and a wide viewing angle can berealized.

The above-described example is directed to the case where the initialalignment direction of liquid crystal molecules LM is parallel to thesecond direction Y. However, the initial alignment direction of liquidcrystal molecules LM may be an oblique direction D which obliquelycrosses the second direction Y, as shown in FIG. 2. An angle Θ formedbetween the second direction Y and the initial alignment direction D is0° or more and 45° or less. From the standpoint of alignment control ofliquid crystal molecules LM, it is desirable that the initial alignmentdirection of liquid crystal molecules LM be a direction in a range of 0°or more and 20° or less, relative to the second direction Y.

The above-described example relates to the case in which the liquidcrystal layer LQ is composed of a liquid crystal material having apositive (positive-type) dielectric constant anisotropy. Alternatively,the liquid crystal layer LQ may be composed of a liquid crystal materialhaving a negative (negative-type) dielectric constant anisotropy.Although a detailed description is omitted, in the case of thenegative-type liquid crystal material, since the positive/negative stateof dielectric constant anisotropy is revered, it is desirable that theabove-described formed angle Θ be within the range of 45° or more and90° or less, preferably the range of 70° or more and 90° or less.

Since a lateral electric field is hardly produced over the pixelelectrode PE or common electrode CE even at the ON time (or an electricfield enough to drive liquid crystal molecules LM is not produced), theliquid crystal molecules scarcely move from the initial alignmentdirection, like the case of the OFF time. Thus, even if the pixelelectrode PE and common electrode CE are formed of a light-transmissiveelectrically conductive material such as ITO, little backlight passesthrough these regions, and these regions hardly contribute to display atthe ON time. Thus, the pixel electrode PE and common electrode CE do notnecessarily need to be formed of a transparent material, and may beformed of an opaque wiring material such as aluminum, silver or copper.

In the above-described example, the structure, in which the storagecapacitance line is disposed immediately below the sub-pixel electrodePB, has been described. However, the gate line may be disposedimmediately below the sub-pixel electrode PB. Specifically, the entiretyof the projection portion PB1 and projection portion PB2 of thesub-pixel electrode PB may be located on the region overlapping the gateline.

In the present embodiment, the structure of the pixel PX is not limitedto the example shown in FIG. 2. Variations of this embodiment will bedescribed below. The pixel electrode PE, main common electrode CAL andmain common electrode CAR are illustrated, and depiction of otherstructural parts is omitted.

FIG. 8 is a plan view which schematically shows another structureexample of the pixel PX at a time when the liquid crystal display panelLPN shown in FIG. 1 is viewed from the counter-substrate side.

This structure example differs from the structure example shown in FIG.2 in that the sub-pixel electrode PB includes second edges E2 havingcurved shapes, which are continuous with the first edges E1. In thiscase, an exterior angle θ1 between the first edge E1 and second edge E2corresponds to an angle θ1 formed between the first edge E1 and atangent of the second edge E2. This formed angle θ1 is an obtuse angle.An angle θ2 formed between a base E23 and the tangent of the second edgeE2 is an acute angle. Each of the projection portion PB1 and projectionportion PB2 includes a pair of oblique lines E21 and E22, which areinclined to the first direction X, and the base E23 which is located onthe same straight line as the first edge E1. Both the linear obliqueline E21 and oblique line E22 are continuous with the second edges E2.The projection portion PB1 includes an apex T1 which is an intersectionbetween the oblique line E21 and oblique line E22. Similarly, theprojection portion PB2 includes an apex T2 which is an intersectionbetween the oblique line E21 and oblique line E22. In some cases, eachof the apex T1 and apex T2 may be rounded.

In the sub-pixel electrode PB with this shape, too, the samerelationship in width, as described with reference to FIG. 3, isestablished. Therefore, in this structure example, too, the sameadvantageous effects as in the above-described example can be obtained.

FIG. 9 is a plan view which schematically shows another structureexample of the pixel PX at a time when the liquid crystal display panelLPN shown in FIG. 1 is viewed from the counter-substrate side.

This structure example differs from the structure example shown in FIG.2 in that each of the projection portion PB1 and projection portion PB2of the sub-pixel electrode PB has a trapezoidal shape. Specifically,each of the projection portion PB1 and projection portion PB2 includes apair of oblique lines E21 and E22, which are inclined to the firstdirection X, a lower base E23 which is located on the same straight lineas the first edge E1, and an upper base E24 which is shorter than thelower base E23. The oblique line E21 and oblique line E22 correspond toa pair of linear second edges E2 which are continuous with the firstedge E1. The length of the oblique line E21 is equal to the length ofthe oblique line E22. The oblique line E21 is not parallel to theoblique line E22. The upper base E24, which is continuous with theoblique line E21 and oblique line E22, is parallel to the seconddirection Y. The upper base E24 of the projection portion PB1 is locatedat a position closest to the source line S1 or main common electrodeCAL. The upper base E24 of the projection portion PB2 is located at aposition closest to the source line S2 or main common electrode CAR.

In this case, the exterior angle θ1 between the first edge E1 and thelinear second edge E2 is an obtuse angle. The exterior angles θ1 at thefour locations illustrated are substantially equal. Accordingly, the sumof the exterior angles θ1 at the four locations is greater than 360°. Inthe meantime, an angle θ2 formed between the base E23 and the tangent ofthe second edge E2 is an acute angle.

If attention is paid to the width of the sub-pixel electrode PB in thefirst direction X, a width W2 in the first direction X between theoblique line E21 of projection portion PB1 and the oblique line E21 ofprojection portion PB2 is greater than a width W1 of the main pixelelectrode PA. A width W3 in the first direction X between the upper baseE24 of the projection portion PB1 and the upper base E24 of theprojection portion PB2 is greater than the width W2 and is a maximumwidth. A width W4 in the first direction X between the oblique line E22of projection portion PB1 and the oblique line E22 of projection portionPB2 is greater than the width W1 of the main pixel electrode PA and issmaller than the width W3. Specifically, the sub-pixel electrode PB hasthe width W3, which is the maximum width in the first direction X, at aposition crossing the upper base E24 of the projection portion.

If attention is paid to the width of the sub-pixel electrode PB in thesecond direction Y, the lower base E23 with a width W11 is longer thanthe upper base E24 with a width 12 in each of the projection portion PB1and projection portion PB2 of the sub-pixel electrode PB. In thisstructure example, too, the same advantageous effects as in theabove-described structure examples can be obtained.

FIG. 10 is a plan view which schematically shows another structureexample of the pixel PX at a time when the liquid crystal display panelLPN shown in FIG. 1 is viewed from the counter-substrate side.

This structure example differs from the structure example shown in FIG.9 in that the sub-pixel electrode PB includes second edges E2 havingcurved shapes, which are continuous with the first edges E1. In thiscase, an exterior angle θ1 between the first edge E1 and second edge E2corresponds to an angle θ1 formed between the first edge E1 and atangent of the second edge E2. This formed angle θ1 is an obtuse angle.Each of the projection portion PB1 and projection portion PB2 includes apair of oblique lines E21 and E22, which are inclined to the firstdirection X, a lower base E23 which is located on the same straight lineas the first edge E1, and an upper base E24 which is shorter than thelower base E23. The linear oblique line E21 and oblique line E22 arecontinuous with the second edges E2. In some cases, an intersectionbetween the oblique line E21 and the upper bottom E24 and anintersection between the oblique line E22 and the upper bottom E24 maybe rounded.

In the sub-pixel electrode PB with this shape, too, the samerelationship in width, as described with reference to FIG. 9, isestablished. Therefore, in this structure example, too, the sameadvantageous effects as in the above-described examples can be obtained.

FIG. 11 is a plan view which schematically shows another structureexample of the pixel PX at a time when the liquid crystal display panelLPN shown in FIG. 1 is viewed from the counter-substrate side.

This structure example differs from the structure example shown in FIG.2 in that each of the projection portion PB1 and projection portion PB2of the sub-pixel electrode PB has a semicircular shape or a semiellipticshape. In this case, an exterior angle θ1 between the first edge E1 ofthe main pixel electrode PA and the second edge E2 of the sub-pixelelectrode PB, which is continuous with the first edge E1, is an obtuseangle. The second edge E2 corresponds to an arc of each of theprojection portion PB1 and projection portion PB2.

In the sub-pixel electrode PB with this shape, too, the samerelationship in width, as described with reference to FIG. 3, isestablished. Therefore, in this structure example, too, the sameadvantageous effects as in the above-described examples can be obtained.

FIG. 12 is a plan view which schematically shows another structureexample of the pixel PX at a time when the liquid crystal display panelLPN shown in FIG. 1 is viewed from the counter-substrate side.

This structure example differs from the structure example shown in FIG.11 in that the sub-pixel electrode PB includes second edges E2 havingcurved shapes, which are continuous with the first edges E1. In thiscase, an exterior angle θ1 between the first edge E1 and second edge E2corresponds to an angle θ1 formed between the first edge E1 and atangent of the second edge E2. This formed angle θ1 is an obtuse angle.

In the sub-pixel electrode PB with this shape, too, the samerelationship in width, as described with reference to FIG. 3, isestablished. Therefore, in this structure example, too, the sameadvantageous effects as in the above-described example can be obtained.

In the structure examples of FIG. 2, and FIG. 8 to FIG. 12, thecombinations between the linear first edge E1 and the linear or curvedsecond edge E2 have been described. In some cases, however, in theprocess of the pixel electrode formation, such as etching, the firstedge E1 and second edge E2 may be formed in a gently curved shape. Inaddition, intersections between lines which define the sub-pixelelectrode PB, such as the intersection between the first edge E1 andsecond edge E2, may be rounded. In the case where both the first edge E1and second edge E2 are curved lines, an angle on the outside of thepixel electrode PE, among the angles formed between the tangent of thefirst edge E1 and the tangent of the second edge E2, is an obtuse angle,and an angle on the inside of the pixel electrode PE is an acute angle.When the first edge E1 and second edge E2 are disposed in this manner,it is possible to suppress the occurrence of a dark part near anintersection between the main pixel electrode PA of the pixel electrodePE included in the array substrate AR and the sub-pixel electrode PBwhich is continuous with the main pixel electrode PA, and to suppress adecrease in transmittance.

FIG. 13 is a plan view which schematically shows a structure example ofthe pixel at a time when the liquid crystal display panel shown in FIG.1 is viewed from the counter-substrate side.

This structure example differs from the structure example shown in FIG.2 in that the counter-substrate CT includes a sub-common electrode CBwhich constitutes the common electrode CE, in addition to the maincommon electrode CA. The sub-common electrode CB is formed integral orcontinuous with the main common electrode CA, and extends in the firstdirection X. The sub-common electrode CB is opposed to each of the gatelines G. In the example illustrated, two sub-common electrodes CB arearranged in parallel with a distance in the second direction Y. Thesub-common electrodes CB include a sub-common electrode CBU which isdisposed at an upper side end portion of the pixel PX, and a sub-commonelectrode CBB which is disposed at a lower side end portion of the pixelPX. The sub-common electrode CBU is opposed to the gate line G1 and isdisposed to extend over a boundary between the pixel PX and a pixelneighboring on the upper side. In addition, the sub-common electrode CBBis opposed to the gate line G2 and is disposed to extend over a boundarybetween the pixel PX and a pixel neighboring on the lower side. Thesub-common electrode CBU and the sub-common electrode CBB are continuouswith the main common electrodes CA and constitute a grid-shaped commonelectrode CE on the counter-substrate CT. In addition, the sub-commonelectrode CBU and the sub-common electrode CBB are, like the main commonelectrodes CA, covered with the second alignment film AL2. In thisstructure example, too, the same advantageous effects as in theabove-described examples can be obtained.

FIG. 14 is a plan view which schematically shows another structureexample at a time when the array substrate AR is viewed from thecounter-substrate side.

This structure example differs from the structure example shown in FIG.2 in that the array substrate AR includes a first shield electrode SE1.The first shield electrode SE1 is electrically connected to the maincommon electrodes CA and is set at the same potential as the main commonelectrodes CA. The first shield electrode SE1 extends in the firstdirection X, and is opposed to each of the gate lines G. In the exampleillustrated, two first shield electrodes SE1 are arranged in parallelwith a distance in the second direction Y. The first shield electrodesSE1 are formed in the same layer as the pixel electrode PE, and can beformed of the same material as the pixel electrode PE. Specifically,when the pixel electrode PE is formed on the second interlayerinsulation film 12 in the example shown in FIG. 4, the first shieldelectrodes SE1 are formed on the second interlayer insulation film 12and are covered with the first alignment film AL1. The first shieldelectrodes SE1 are spaced apart from the pixel electrode PE.

In this structure example, the same advantageous effects as in theabove-described examples can be obtained. Furthermore, with theprovision of the first shield electrodes SE1, an undesired electricfield from the gate lines G can be shielded. Therefore, the degradationin display quality can further be suppressed.

FIG. 15 is a plan view which schematically shows another structureexample at a time when the array substrate AR is viewed from thecounter-substrate side.

This structure example differs from the structure example shown in FIG.14 in that the array substrate AR includes a second shield electrode SE1in addition to the first shield electrode SE1. The second shieldelectrode SE2 is continuous with the first shield electrode SE1, and isset at the same potential as the main common electrodes CA. In addition,the second shield electrode SE2 extends in the second direction Y, andis opposed to each of the source lines S. In the example illustrated,two second shield electrodes SE2 are arranged in parallel with adistance in the first direction X. The second shield electrodes SE2 areformed in the same layer as the pixel electrode PE, and can be formed ofthe same material as the pixel electrode PE. Specifically, the secondshield electrodes SE2 are formed on the second interlayer insulationfilm 12 and are covered with the first alignment film AL1. The secondshield electrodes SE2 are spaced apart from the pixel electrode PE.Specifically, the sub-pixel electrode PB is disposed near the secondshield electrodes SE2, but is spaced apart from the second shieldelectrodes SE2.

In this structure example, the same advantageous effects as in theabove-described examples can be obtained. Furthermore, with theprovision of the second shield electrodes SE2, an undesired electricfield from the source lines S can be shielded. Therefore, thedegradation in display quality can further be suppressed.

The sub-pixel electrodes PB shown in FIG. 13 to FIG. 15 have the sameshape as in the structure example shown in FIG. 10. However, thesub-pixel electrodes PB shown in FIG. 13 to FIG. 15 may have the sameshape as in the structure examples shown in FIG. 2, FIG. 8, FIG. 9, FIG.11 and FIG. 12.

FIG. 16 is a plan view which schematically shows another structureexample at a time when the array substrate AR is viewed from thecounter-substrate side.

This structure example differs from the structure example shown in FIG.2 in that the pixel electrode PE is formed in a T shape. The main pixelelectrode PA is formed in a straight line shape along the seconddirection Y from one end portion on the gate line G1 side to the otherend portion on the gate line G2 side. A sub-pixel electrode PB isopposed to the storage capacitance line C1, and crosses one end portionin the second direction Y of the main pixel electrode PA. The sub-pixelelectrode PB includes a projection portion PB1 which protrudes from theintersection with the main pixel electrode PA toward the source line S1,and a projection portion PB2 which protrudes from the intersection withthe main pixel electrode PA toward the source line S2. The projectionportion PB1 and projection portion PB2 have an identical shape. Thesub-pixel electrode PB includes second edges E2 which are continuouswith the first edges E1.

In the pixel electrode PE with this shape, an exterior angle θ1 isformed at two locations between the main pixel electrode PA and thesub-pixel electrode PB. The exterior angle θ1 corresponds to an angleformed between the first edge E1 and the second edge E2. Each of theexterior angles θ1 formed at the two locations is an obtuse angle whichis greater than 90°, and the exterior angles θ1 at the two locations aresubstantially equal.

A width W2 of the sub-pixel electrode PB in the first direction X isgreater than the width W1 of the main pixel electrode PA. The sub-pixelelectrode PB has a width W3, which is a maximum width in the firstdirection X, at a central part in the second direction Y. The projectionportion PB1 of the sub-pixel electrode PB has a width W11 at a positionon the main pixel electrode PA side, and a width W12, which is less thanthe width W11, at a position on the source line S1 side or a position onthe main common electrode CAL side. Similarly, the projection portionPB2 of the sub-pixel electrode PB has a width W11 at a position on themain pixel electrode PA side, and a width W12, which is less than thewidth W11, at a position on the source line S2 side or a position on themain common electrode CAR side.

In this structure example, the number of domains, which are formed inone pixel, is less than in the structure examples shown in FIG. 2, etc.,but the occurrence of a dark part can be suppressed and the sameadvantageous effects as in the above-described structure examples can beobtained.

The array substrates AR of the structure examples shown in FIG. 14 toFIG. 16 may be combined with the counter-substrate CT including the maincommon electrodes CA shown in FIG. 2, or may be combined with thecounter-substrate CT including the main common electrodes CA andsub-common electrodes CB shown in FIG. 13.

As has been described above, according to the present embodiments, aliquid crystal display device which has a good display quality can beprovided.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A liquid crystal display device comprising: afirst substrate including a strip-shaped main pixel electrode having afirst width in a first direction and linearly extending in a seconddirection crossing the first direction, the main pixel electrodeincluding a first edge extending in the second direction, the firstsubstrate further including a sub-pixel electrode crossing the mainpixel electrode and protruding from the first edge in the firstdirection, and a first alignment film covering the main pixel electrodeand the sub-pixel electrode; a second substrate including main commonelectrodes extending substantially parallel to the main pixel electrodeon both sides of the main pixel electrode, and a second alignment filmcovering the main common electrodes; and a liquid crystal layerincluding liquid crystal molecules held between the first substrate andthe second substrate, wherein the sub-pixel electrode has a secondwidth, which is greater than the first width, in the first direction,has a third width, which is a maximum width in the first direction, at acentral portion of the sub-pixel electrode, has a fourth width in thesecond direction at a position with a first distance from the first edgein the first direction, and has a fifth width, which is less than thefourth width, at a position at a second distance, which is greater thanthe first distance, from the first edge in the first direction, thesub-pixel electrode includes projection portions protruding on bothsides of the main pixel electrode, and each of the projection portionshas a triangular shape including a pair of oblique lines which areinclined to the first direction, and a base which is located on the samestraight line as the first edge.
 2. The liquid crystal display device ofclaim 1, wherein the sub-pixel electrode crosses an intermediate portionin the second direction of the main pixel electrode.
 3. The liquidcrystal display device of claim 2, wherein a sum of four exterior anglesbetween the main pixel electrode and the sub-pixel electrode is greaterthan 360°.
 4. The liquid crystal display device of claim 1, wherein theprojection portions, which are located on both sides of the main pixelelectrode, have an identical shape.
 5. The liquid crystal display deviceof claim 1, wherein the sub-pixel electrode includes a second edge whichis continuous with the first edge, and an exterior angle between thefirst edge and the second edge is an obtuse angle.
 6. The liquid crystaldisplay device of claim 1, wherein the first substrate further includesa gate line extending in the first direction, and a first shieldelectrode which is set at the same potential as the main commonelectrode, extends in the first direction, is opposed to the gate line,and is covered with the first alignment film.
 7. The liquid crystaldisplay device of claim 1, wherein the first substrate further includesa source line extending in the second direction, and a second shieldelectrode which is set at the same potential as the main commonelectrode, extends in the second direction, is opposed to the sourceline, and is covered with the first alignment film.
 8. The liquidcrystal display device of claim 1, wherein the first substrate furtherincludes a gate line and a storage capacitance line which extend in thefirst direction, a source line extending in the second direction, and aswitching element electrically connected to the gate line and the sourceline, and the sub-pixel electrode is opposed to the storage capacitanceline and is electrically connected to the switching element.
 9. Theliquid crystal display device of claim 1, wherein the second substrateincludes a sub-common electrode which is continuous with the main commonelectrode, extends in the first direction, and is covered with thesecond alignment film.
 10. A liquid crystal display device comprising: afirst substrate including a strip-shaped main pixel electrode having afirst width in a first direction and linearly extending in a seconddirection crossing the first direction, the main pixel electrodeincluding a first edge extending in the second direction, the firstsubstrate further including a sub-pixel electrode crossing the mainpixel electrode and protruding from the first edge in the firstdirection, and a first alignment film covering the main pixel electrodeand the sub-pixel electrode; a second substrate including main commonelectrodes extending substantially parallel to the main pixel electrodeon both sides of the main pixel electrode, and a second alignment filmcovering the main common electrodes; and a liquid crystal layerincluding liquid crystal molecules held between the first substrate andthe second substrate, wherein the sub-pixel electrode has a secondwidth, which is greater than the first width, in the first direction,has a third width, which is a maximum width in the first direction, at acentral portion of the sub-pixel electrode, has a fourth width in thesecond direction at a position at a first distance from the first edgein the first direction, and has a fifth width, which is less than thefourth width, at a position at a second distance, which is greater thanthe first distance, from the first edge in the first direction, thesub-pixel electrode includes projection portions protruding on bothsides of the main pixel electrode, and each of the projection portionshas a semicircular shape or a semielliptic shape.
 11. The liquid crystaldisplay device of claim 10, wherein the sub-pixel electrode crosses anintermediate portion in the second direction of the main pixelelectrode.
 12. The liquid crystal display device of claim 11, wherein asum of four exterior angles between the main pixel electrode and thesub-pixel electrode is greater than 360°.
 13. The liquid crystal displaydevice of claim 10, wherein the projection portions, which are locatedon both sides of the main pixel electrode, have an identical shape. 14.The liquid crystal display device of claim 10, wherein the sub-pixelelectrode includes a second edge which is continuous with the firstedge, and an exterior angle between the first edge and the second edgeis an obtuse angle.
 15. The liquid crystal display device of claim 10,wherein the first substrate further includes a gate line extending inthe first direction, and a first shield electrode which is set at thesame potential as the main common electrode, extends in the firstdirection, is opposed to the gate line, and is covered with the firstalignment film.
 16. The liquid crystal display device of claim 10,wherein the first substrate further includes a source line extending inthe second direction, and a second shield electrode which is set at thesame potential as the main common electrode, extends in the seconddirection, is opposed to the source line, and is covered with the firstalignment film.
 17. The liquid crystal display device of claim 10,wherein the first substrate further includes a gate line and a storagecapacitance line which extend in the first direction, a source lineextending in the second direction, and a switching element electricallyconnected to the gate line and the source line, and the sub-pixelelectrode is opposed to the storage capacitance line and is electricallyconnected to the switching element.
 18. The liquid crystal displaydevice of claim 10, wherein the second substrate includes a sub-commonelectrode which is continuous with the main common electrode, extends inthe first direction, and is covered with the second alignment film. 19.A liquid crystal display device comprising: a first substrate includinga first wiring line and a second wiring line which are separated fromeach other by a distance in a first direction and extend in a seconddirection crossing the first direction, a strip-shaped main pixelelectrode which is disposed between the first wiring line and the secondwiring line and includes a first edge linearly extending in the seconddirection, and a sub-pixel electrode which includes a second edgeextending in a direction different from the direction of extension ofthe first edge, the second edge being continuous with the first edge; asecond substrate including main common electrodes which are opposed tothe first wiring line and the second wiring line and extendsubstantially parallel to the main pixel electrode; and a liquid crystallayer including liquid crystal molecules held between the firstsubstrate and the second substrate, wherein an exterior angle betweenthe first edge and the second edge is an obtuse angle, and the exteriorangle is an angle formed between the first edge and a tangent of thesecond edge having a curved shape.
 20. The liquid crystal display deviceof claim 19, wherein a sum of four exterior angles between the mainpixel electrode and the sub-pixel electrode is greater than 360°. 21.The liquid crystal display device of claim 19, wherein the firstsubstrate further includes a gate line extending in the first direction,and a first shield electrode which is set at the same potential as themain common electrode, extends in the first direction, and is opposed tothe gate line.
 22. The liquid crystal display device of claim 19,wherein the first substrate further includes a second shield electrodewhich is set at the same potential as the main common electrode, extendsin the second direction, is opposed to the first wiring line.
 23. Theliquid crystal display device of claim 19, wherein the first substratefurther includes a gate line and a storage capacitance line which extendin the first direction, and a switching element electrically connectedto the gate line and the first wiring line, and the sub-pixel electrodeis opposed to the storage capacitance line and is electrically connectedto the switching element.
 24. The liquid crystal display device of claim19, wherein the second substrate includes a sub-common electrode whichis continuous with the main common electrode, and extends in the firstdirection.
 25. A liquid crystal display device comprising: a firstsubstrate including a first wiring line and a second wiring line whichare separated from each other by a distance in a first direction andextend in a second direction crossing the first direction, astrip-shaped main pixel electrode which is disposed between the firstwiring line and the second wiring line, has a first width in the firstdirection and linearly extends in the second direction, and a sub-pixelelectrode which crosses one end portion in the second direction of themain pixel electrode and includes projection portions protruding towardthe first wiring line and the second wiring line; a second substrateincluding main common electrodes which are opposed to the first wiringline and the second wiring line and extend substantially parallel to themain pixel electrode; and a liquid crystal layer including liquidcrystal molecules held between the first substrate and the secondsubstrate, wherein the sub-pixel electrode has a second width, which isgreater than the first width, in the first direction, has a third width,which is a maximum width in the first direction, at a central portion ofthe sub-pixel electrode, has a fourth width in the second direction onthe main pixel electrode side, and has a fifth width, which is less thanthe fourth width, in the second direction on the first wiring line sideand on the second wiring line side.
 26. The liquid crystal displaydevice of claim 25, wherein the projection portions, which are locatedon both side of the main pixel electrode, have an identical shape. 27.The liquid crystal display device of claim 25, wherein the main pixelelectrode includes a first edge linearly extending in the seconddirection, the sub-pixel electrode includes a second edge which iscontinuous with the first edge, and an exterior angle between the firstedge and the second edge is an obtuse angle.
 28. The liquid crystaldisplay device of claim 25, wherein the first substrate further includesa gate line extending in the first direction, and a first shieldelectrode which is set at the same potential as the main commonelectrode, extends in the first direction, and is opposed to the gateline.
 29. The liquid crystal display device of claim 25, wherein thefirst substrate further includes a second shield electrode which is setat the same potential as the main common electrode, extends in thesecond direction, is opposed to the first wiring line.
 30. The liquidcrystal display device of claim 25, wherein the first substrate furtherincludes a gate line and a storage capacitance line which extend in thefirst direction, and a switching element electrically connected to thegate line and the first wiring line, and the sub-pixel electrode isopposed to the storage capacitance line and is electrically connected tothe switching element.
 31. The liquid crystal display device of claim25, wherein the second substrate includes a sub-common electrode whichis continuous with the main common electrode, and extends in the firstdirection.